There are basically two types of return which is to be filed by a professional, either ITR 4 if he chooses for the maintenance and audit of accounts else ITR 4S if he do not choose the same. So, if you are maintaining your books of accounts and getting your accounts audited then you need to file ITR-4 else you have to file ITR 4S using presumptive source of income.
Last date for filing the business and profession income return is normally 31st July of the Assessment Year but if you are required to get your accounts audited, then last date for filing of return of income is 30th September of Assessment Year.
If you are engaged in a specified profession(specified in Q4), then you need to maintain the books of accounts if your gross receipts exceeds Rs. 1,50,000 in all the three years immediately preceding the previous year or if you are going to start a new business then gross receipts is likely to exceed Rs.1,50,000.
Specified Profession include legal, medical, engineering, architectural, accountancy, technical, interior decoration, film artists, company secretary, information technology and authorised representatives profession.
You can opt for presumptive source of income if your turnover or gross receipts is within the specified limits(given in Q6), or if you are engaged in a business of plying, hiring or leasing of goods/carriages, then you can opt for presumptive source of income.
You are required to get your accounts audited if your turnover or gross receipts exceeds Rs. 2 Cr.(in case of Business) and Rs. 50 lakhs(in case of profession).
You have to maintain books of accounts and get your accounts audited if you do not opt for presumptive source of income, though eligible.